Furnace thermostat switch



L E. SMITH JN w E. mm NN QN wN lNvENToR ESI/ruik um ATTORNEY July 27,1926.

FURNACE THERMOSTAT `SWITCH Filed Sept. 5.

Patented July 27, 1926. y i

U'NITED'STATES PATENT OFFICE.

IBA EDWARD SMITH, F BTOCKTON, CALIFORNIA.

IURNACE THERHOBTAT BWITCE.

' Application med september s,.- iaas. semina. 55,0311.

- switch fundamentally comprised a plurality of mercury containingtubes, having contacts mounted at varying angles and arranged as a unitto bev rotated upon the expandin of the thermostatic element. I retainthis fundamental construction but have provided, however, certain imortant changes in the thermostatic means or operatin said switch contactunit. In t e previous switchthe initial movement of the switch tube unitwhich controlled the closing of the switch startin the sparkingandelectric heating devices o the burner, was had by electrically heatingthe thermostatic element itself to a degree necessary to im art thedesired rotation to the tube unit. his consumed considerable current andan appreciable time elapsed before such. rotation took lace.

The princi al o ject of my present invention there ore is to provide amore simple and quicker operating means for initially rotating the tubeunit, so that less current is used and there is less delay between theinitial turnin on of the current and ,the functioning o the burner.

I have also redesigned the arran ement' of the main thermostat relativeto e switch .tube unit, so that much shorter len hs of 'l the expansibleand nonexpansible e ements may be used, while at the same time. Iarrange for ample movement of the member which controls the majorrotation of said tube unit. 4

A further object of the invention is to produce a sim le and inexpensivedevice and yet one which will be exceedin ly effecsuch structure andrelative `arrangement of,

tive for the signed. These objects I accomplish'by means of purpose forwhich itis departs as will fully appear by a lrusal of the followingspecification and claliiiis., .i l.

In the drawings similar characters of ref-` erence indicatecorresponding .parts 'in the several views:

Fig. 1 is a side view of my improved type `4 extends upwardly, an elwardly inside the vand is of thermostat switch, showing the same asmounted Vin connection with a furnace.

Fig. 2 is a side view of the device detached, partly broken out and linsection with the parts in their normal or cold positions.

. Fig.- 3 is a top plan view of the devicebetter From the lower end andadjacent one side of said platea horizontal pipe 2 projects, having abracket 3 by means of which these parts may be supported in a fixedosition. At the outer 'end of the pipe 2 anot er pipe ow 5 connectingthe adjacent ends of both pipes. Another length ofhorizontal pi e 6extends from beyond the upper end o the pipe 4, with an elbow 7connecting the ad}acent ends of these` i s. f'

' A rigid rod 8 is mounted in the pipe 6 supported therefrom only at theouter end of t e latter. At its opposite end the rod 8 is supported fromone arm of a bellcrank 9 which is mounted in the elbow 7. Another rod 10is supported from the other arm of the bellcrank 9 and .extends downpi e4 to a connection with one arm of abeilcrank 11 mounted in the elbow 5.The opposite end of the bellcrank 11 is connected to a rod 12 whichismounted in the pipe 2 and projects through the same to a termination)ust inwardly of the plate 1.

The various rods are supported from the bell-cranks and pipe 6 in thefollowing manner:

In the outer end of pipe 6 is a nut 6* having a needle point 6 on itsinner end engaging a socket in the corresponding end of a shoulder orbushing 2 in which rod l2 is slidable, and a com ression spring 12labout said rod beyond t e shoulder and bearing thereagainst and againsta collar 12h on the rod tends to retract the rod away from the innerface of the plate 1, and serves to hold all the needle oint bearings infirm engagement with eac other, re ardless of the expansion orcontraction o the pipe 6.

The device is mounted in connection with a furnace box 13 in which anoil' burner is located, so that the pipe 2 enters the furnace at the ashbox, the pipe 4 extends upwardly along the inside of the furnace, andthe pipe 6 projects across the furnace above the burner. s

The pipe 6 is therefore located so as to be subjected to the direct heatof the burner,

the other pipes being heated to a much lesser4 de ree.

he ipe 6 and rod 8 form the maln thermostatic elements of my device. Thepipe 6 is preferably made of nichrome steel--v anl element capable .ofexpanding under heat but offering considerable resistance todisintegration by reason of such heat. The rod 8 is preferably made offused silicaan element of practically non-expansible nature. It willtherefore be seen that if the pipe 6 expands relative tc the rod 8,relative movement between the bellcrank end of said rod 8 and theadjacent end of the pipe 6 will be had. This causes the turning of theadjacent bellcrank on its pivot, and conse uentlya longitudinal movementof the rdd 10; a turning of the bellcrank 1l; and a lon itudinalmovement of the rod 12 will be ad in their respective enclosures. Theparts are so arranged that when the pi e 6 is heated, the outer end ofthe rod 12 w1ll recede in the pipe 2.

Owing to the use of bellcranks whose arms maybe., designed to give anydesired lever- ""age, the length of the elements 6 and 8,

and consequently? the amount of relative movement therebetween, may bevery'short, and still provide for considerable movement of the free endof the rod 12. The pipes 2 and 4 and the corresponding rods are made ofordinary steel so that expansion and contraction, if any, will be thesame throughout and will not affect the result.

Turnably supported from the plate 1 and disposed below the plane of therod 12 and at right angles thereto is a horizontal shaft 14. A short arm15 projects upwardly from said shaft and is bent at its upper end toextend toward and abut against the adjacent end of the rod 12.

A spring 16 about said shaft acts to hold the arm 15 in engagement withthe rod 12 and to rotate said shaft when the rod recedes.

Brackets 17 project horizontally from the plate 1 adjacent the sidesthereof a certain distance above the rod 12, in which brackets isturnably mounted a supporting structure having a plurality ofswitch-contact mem- These v'members are in the form of tubes 19, set atdifferent angles relative to each other, and having contacts 20projecting thereinto, certain ones of which contacts are lnormallyimmersed in mercury 21 sealed in the tubes but not filling the same.

This switch structure, its mounting, functioning and connection with theoil burner circuits, has been fully set forth in the copending aplication before mentioned, and therefore oes not need to be enlarged-upon here. It is believed to be sufficient to state that after arotation of the structure 18 in a certain direction from a normal orcold position, the contacts will be broken or opened one after theother, by a change of level of the tubes, and a consequent flowing ofthe mercury away from the contacts.

vRotation is imparted to the structure 18 to effect such movement of thetubes in the following manner:

Projecting tangentially from and affixed to the shaft 14 adjacent oneend thereof is an arm 22 to whose outer end is pivoted a rack 23 whichengages a gear 24 fixed on' the corresponding end of the structure 18.The arm 22 is in itself a bimetal thermostat element, consisting of twosuperim osed metal strips A and B, the lower strip expanding to agreater extent than the other. A wire 25 is wound about the strips toform a coil 'heating element, and is electricall 'i insulated from saidstrips. When this coil is heated the arm 22 is heated also, causing thearm to assume a curved form from end to end with the upper face concave.Since the shaft 14 is stationary the arm 22 can' only move up at itsother end, which will cause the rack 23 to move up and consequentlyimpart rotation to the structure` 18. The wires 25 of the heating coilare connected in series with the wires of the contacts of that tube 19whose contacts will be first broken with the rotation of the structure18. These contacts are also in the circuit of the main starting switchof the system.

In operation therefore when such starting switch is closed, the arm 22is heated, the structure 18 is rotated to break the first contact asabove stated, which breaks the heater circuit. At the same time, asstated in the previous application, such rotation of the structure 18has closed electric heating and sparking devices of the oil burner, andthe latter is then set in operation. The heat from the burnerimmediately and directly affects the thermostat elements 6 and 8 so 14will be rotated a distance enough lto compensate for the retractingtendency of the rack had with the cooling olf of the arm 22.

Thereafter with the further heatin of the main thermostat elements inthe urnace, the arm 22 is rigid and inactive, and merely serves as anoperating means for the rack 23 with the rotation of the shaft.

The arm 22 being small, the current and time necessary to cause the sameto be heated and to function as above stated, are very small, and aquick starting of the burner into actual operation results from the useof this device.

, Owing to the use of agear on the switch of the invention as set forthherein.

While this specification sets forth in de` tail the present andpreferred construction of the device, still in practice such' deviationsfrom such detail may be resorted to as do not form a de arture from thespirit ofthe invention, as ened by the appended claims.

Having thus described my invention what I claim as new and useful and-desire to secure by Letters Patent is:

1. A thermostat switch including expansible and nonexpansible elementsmounted together for relative longitudinal movement when subjected tothe influence of heat, al

v shaft, means whereby said shaft will be rotated upon the expansion ofsaid element, an arm projecting substantially radially from the shaft, arotatable switch Contact structure whose axis of rotation is located ina plane parallel to but vertically spaced from said shaft, means wherebythe contacts will be opened when said structure is rotated from a(predetermined osition, a gear fixed on sai structure axia ly thereofand a rack projecting from the outer end of the arm at an' angle theretoand engaging the gear, whereby the shaft when rotated will cause anarcuate movement of the arm and a consequent longitudinal movement ofthe rack and a rotation of the gear and switch structure.

2. A structure as in claim 1, in which said arm is of bimetalconstruction, and means is applied thereto for heating the same; saidarm eing so arranged as to cause the same when heated, to movev the rackand rotate the gear and switch structure regardless of any movement ofthe shaft.

3. A thermostat switch including expansive and -nonexpansive elementsmounted together for relative longitudinal movement when subjected tothe influence of heat, a rotatable switch contactv structure mounted inconnection with said elements, means whereby the contacts `will beopened when said structure is rotated to a certain extent from apredetermined osition, means between the elements and) the structure forcausing the latter to be rotated when said elements are heated, andthermostatic means for enabling said structure to be rotated independentof heat applied to the said elements.

4. Operating means for a thermostat switch which includes a movable,member whose movement causes the contacts to be opened, comprisingexpansive and nonexpensive elements mounted together for rnlativelongitudinal movement whenl subjected to the influence of heat, theexpansible element being in the form of a tube of nichrome steel, andthe nonex ansible element being in the form of a ro of fused silicadisposed within the tube; said elements being operatively connected tothe movable member of the switch to impart movement thereto with therelative movement between the elements.

5. A thermostat switch including expansive and nonexpa-nsi've elementsmounted together for relative longitudinal movement when subjected tothe influence of heat, a rotatable switch contact structure mounted inconnection With said elements, means whereby the contacts will be opened.when said structure is rotated to a certain extent from a predeterminedposition, a relatively movable rod, means between the rod and thestructure for causing the latter to be rotated when said elements areheated, and connections between` said rod and the elements for enablingthe extenty of movement of the rod to be greater than the movementbetween the elements themselves.

6. A structure as in claim 5, in which said last named means comprises apipe surrounding the rod, another y pipe extending at an an le to thefirst pipe, hollow connections etween the adjacent ends of the pipeandbetween the opposite end of the ast named pipe and the expansibleelement,

together for relative longitudinal movement y when subjected to theinfluence of heat, a shaft, means whereby said shaft will be rotatedvupon the expansion of said element,

an arm projecting from the shaft', a rotatable switch-contact structuremounted in connection with the shaft, means whereby the contacts will beopened when said strueture is rotated to a certain extent from apredetermined position, means between the arm and structure for causingthe latter to be rotated with a movement of the arm caused by therotation of the shaft, and means provided in connection with the arm forcausing the same to move to rotate the structure independent of anyrotation of the shaft.

In testimony whereof I aix my signature.`

' IRA EDWARD SMITH.

